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Quasi-equilibrium closure hierarchies for the Boltzmann equation

Gorban, Alexander N. and Karlin, Iliya V. (2006) Quasi-equilibrium closure hierarchies for the Boltzmann equation Physica A: Statistical Mechanics and its Applications, 360, (2), pp. 325-364. (doi:10.1016/j.physa.2005.07.016).

Record type: Article


In this paper, explicit method of constructing approximations (the triangle entropy method) is developed for nonequilibrium problems. This method enables one to treat any complicated nonlinear functionals that fit best the physics of a problem (such as, for example, rates of processes) as new independent variables. The work of the method is demonstrated on the Boltzmann's-type kinetics. New macroscopic variables are introduced (moments of the Boltzmann collision integral, or scattering rates). They are treated as independent variables rather than as infinite moment series. This approach gives the complete account of rates of scattering processes. Transport equations for scattering rates are obtained (the second hydrodynamic chain), similar to the usual moment chain (the first hydrodynamic chain). Various examples of the closure of the first, of the second, and of the mixed hydrodynamic chains are considered for the hard sphere model. It is shown, in particular, that the complete account of scattering processes leads to a renormalization of transport coefficients. The method gives the explicit solution for the closure problem, provides thermodynamic properties of reduced models, and can be applied to any kinetic equation with a thermodynamic Lyapunov function.

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Submitted date: 31 January 2005
Published date: 1 February 2006
Keywords: entropy, MaxEnt, kinetics, Boltzmann equation, Fokker–Planck equation, model reduction


Local EPrints ID: 49240
ISSN: 0378-4371
PURE UUID: afab4bb7-ad7f-42d9-88c2-19737f523b34

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Date deposited: 25 Oct 2007
Last modified: 17 Jul 2017 14:56

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Author: Alexander N. Gorban
Author: Iliya V. Karlin

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